The present invention relates to an optical zoom device and operational methods for the device.
Conventional zoom devices require coupled mechanical motions to adjust the axial separations between individual or groups of elements in order to change the optical magnification.
FIG. 1 illustrates conventional mechanical zoom system. At the very basic level, a zoom system includes at least one moving lens for zooming. One lens to change the image size is called the variator 1 and another lens to maintain focus through the zoom range is called the compensator 2. The variator 1 is moved to change the image size of object. However, the image is defocused because the imaging position is also changed. Therefore, the variator 1 must move in unison with the compensator lens 2 to zoom and keep the image 3 in focus. These movements are usually mechanically controlled by a zoom ring on the lens barrel.
The mechanical motions decrease the speed of zooming, increase space and weight for zoom system, may induce unwanted jitter, and require large power consumption. In addition, the mechanical zoom system is restricted to magnifying the area on-axis. Therefore, there has been a need for a small and fast zoom device that can change magnification.